import { useRef, useEffect, useState, useCallback } from "react";

interface WaveformPlayerProps {
  audioUrl: string;
  duration?: number | null;
}

export default function WaveformPlayer({ audioUrl, duration }: WaveformPlayerProps) {
  const canvasRef = useRef<HTMLCanvasElement>(null);
  const audioRef = useRef<HTMLAudioElement>(null);
  const animRef = useRef<number>(0);
  const waveformRef = useRef<number[]>([]);

  const [playing, setPlaying] = useState(false);
  const [currentTime, setCurrTime] = useState(0);
  const [totalDuration, setTotalDuration] = useState(0);
  const [hovering, setHovering] = useState(false);
  const [hoverX, setHoverX] = useState(0);

  // Decode audio and compute waveform peaks
  useEffect(() => {
    if (!audioUrl) return;
    const ctx = new AudioContext();
    fetch(audioUrl)
      .then((r) => r.arrayBuffer())
      .then((buf) => ctx.decodeAudioData(buf))
      .then((decoded) => {
        const raw = decoded.getChannelData(0);
        const bars = 100;
        const blockSize = Math.floor(raw.length / bars);
        const peaks: number[] = [];
        for (let i = 0; i < bars; i++) {
          let sum = 0;
          for (let j = 0; j < blockSize; j++) {
            sum += Math.abs(raw[i * blockSize + j]);
          }
          peaks.push(sum / blockSize);
        }
        // Normalize
        const max = Math.max(...peaks, 0.01);
        waveformRef.current = peaks.map((p) => p / max);
        drawWaveform();
        ctx.close();
      })
      .catch(() => {});
  }, [audioUrl]);

  const drawWaveform = useCallback(() => {
    const canvas = canvasRef.current;
    if (!canvas) return;
    const ctx = canvas.getContext("2d");
    if (!ctx) return;

    const dpr = window.devicePixelRatio || 1;
    const rect = canvas.getBoundingClientRect();
    canvas.width = rect.width * dpr;
    canvas.height = rect.height * dpr;
    ctx.scale(dpr, dpr);

    const w = rect.width;
    const h = rect.height;
    const peaks = waveformRef.current;
    const bars = peaks.length || 1;
    const audio = audioRef.current;
    const progress = audio && audio.duration ? audio.currentTime / audio.duration : 0;

    ctx.clearRect(0, 0, w, h);

    const barWidth = (w / bars) * 0.7;
    const gap = (w / bars) * 0.3;
    const mid = h / 2;

    for (let i = 0; i < bars; i++) {
      const x = (i / bars) * w;
      const barH = Math.max(2, (peaks[i] || 0) * mid * 0.9);
      const iPlayed = i / bars < progress;

      ctx.fillStyle = iPlayed ? "#c084fc" : hovering && x < hoverX ? "rgba(192,132,252,0.4)" : "#444";
      ctx.beginPath();
      ctx.roundRect(x + gap / 2, mid - barH, barWidth, barH * 2, 1.5);
      ctx.fill();
    }
  }, [hovering, hoverX]);

  // Animation loop
  useEffect(() => {
    const tick = () => {
      const audio = audioRef.current;
      if (audio) setCurrTime(audio.currentTime);
      drawWaveform();
      animRef.current = requestAnimationFrame(tick);
    };
    animRef.current = requestAnimationFrame(tick);
    return () => cancelAnimationFrame(animRef.current);
  }, [drawWaveform]);

  const togglePlay = () => {
    const audio = audioRef.current;
    if (!audio) return;
    if (audio.paused) {
      audio.play();
      setPlaying(true);
    } else {
      audio.pause();
      setPlaying(false);
    }
  };

  const seek = (e: React.MouseEvent<HTMLCanvasElement>) => {
    const audio = audioRef.current;
    const canvas = canvasRef.current;
    if (!audio || !canvas || !audio.duration) return;
    const rect = canvas.getBoundingClientRect();
    const ratio = (e.clientX - rect.left) / rect.width;
    audio.currentTime = ratio * audio.duration;
  };

  const handleMouseMove = (e: React.MouseEvent<HTMLCanvasElement>) => {
    const canvas = canvasRef.current;
    if (!canvas) return;
    const rect = canvas.getBoundingClientRect();
    setHoverX(e.clientX - rect.left);
  };

  const fmt = (s: number) => {
    const m = Math.floor(s / 60);
    const sec = Math.floor(s % 60);
    return `${m}:${sec.toString().padStart(2, "0")}`;
  };

  return (
    <div className="waveform-player">
      <audio
        ref={audioRef}
        src={audioUrl}
        onLoadedMetadata={() => setTotalDuration(audioRef.current?.duration || 0)}
        onEnded={() => setPlaying(false)}
      />

      <button className="waveform-play" onClick={togglePlay} aria-label={playing ? "Pause" : "Play"}>
        {playing ? (
          <svg width="16" height="16" viewBox="0 0 16 16" fill="currentColor">
            <rect x="3" y="2" width="4" height="12" rx="1" />
            <rect x="9" y="2" width="4" height="12" rx="1" />
          </svg>
        ) : (
          <svg width="16" height="16" viewBox="0 0 16 16" fill="currentColor">
            <path d="M4 2.5v11l9-5.5z" />
          </svg>
        )}
      </button>

      <canvas
        ref={canvasRef}
        className="waveform-canvas"
        onClick={seek}
        onMouseEnter={() => setHovering(true)}
        onMouseLeave={() => setHovering(false)}
        onMouseMove={handleMouseMove}
      />

      <span className="waveform-time">
        {fmt(currentTime)} / {fmt(totalDuration)}
      </span>

      {duration !== null && duration !== undefined && (
        <span className="waveform-gen-time">
          {(duration / 1000).toFixed(1)}s
        </span>
      )}
    </div>
  );
}